The present application relates to an apparatus for communicating another device, and particularly relates to an apparatus having EMI protection mechanism.
EMI (Electromagnetic Interference) is a common problem that can be found in almost every electronic apparatus. EMI is a disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit. The EMI source may be any object, artificial or natural, that carries rapidly changing electrical currents, such as an electrical circuit, the Sun or the Northern Lights.
FIG. 1 is a block diagram illustrating an example of how EMI issue occurs. As shown in FIG. 1, chip 101 transmits or receives data or clock signal to and from the chip 103. The chip 101 and the chip 103 may respectively couple to antennas 102, 104 for receiving respective RF signals. Resistance circuits 105 (only one of them is symbolized) which may include resistor, inductance devices or capacitors are placed on a printed circuit board (PCB), and connect the chips 101 and 103 through traces. A die 107 is encapsulated in the chip 101. The die 107 includes a plurality of bounding pads. The bonding pads of the die 107 are electrically connected to input/output pins 109, 111, 113 through bonding wires 115, 117, 119.
As the electronic devices shown in FIG. 1, the signals transmitted in regions A, B and E may suffer EMI effect caused by the signals transmitted in regions C and D. Many solutions are developed to solve the EMI problem. For example, adding a balun or a saw filter to the region A, or adding a shielding to surround the chip would be favorable. Alternatively, optimizing RF architecture, antenna layout, bounding wire length or signal transmitting waveform can be helpful on reducing EMI effect. However, these methods need either extra hardware cost or complex design.